Electromagnetically operated actuators include at least one electromagnet and an armature which affects a setting member and which is connected with at least one resetting means so that, in response to the energization of the electromagnet, the armature is moved from a first setting position determined by the resetting means into a second setting position in which the armature abuts the pole face of the electromagnet. Electromagnetic actuators of this type are used, for example, for controlling the cylinder valves of a piston-type internal-combustion engine. For such an application, preferably two electromagnets are used between which the armature may be moved into the first and second setting positions back and forth against the force of the resetting means, such as a resetting spring, as the coil current of the holding electromagnet is turned off and the coil current of the capturing electromagnet is turned on. By a suitable actuation of the individual actuators of the cylinder valves, the inflow of the fluid medium into and its outflow from the cylinder may be controlled in such a manner that the work process is optimally influenced to meet any operational requirements. Electromagnetically operated actuators for cylinder valves are disclosed, for example, in U.S. Pat. No. 4,455,543.
In electromagnetic actuators of the above-outlined type the armature arrives in an abutting relationship with the pole face of the momentarily capturing electromagnet in each of the setting positions. Since for a secure capturing of the armature a minimum armature speed has to be present even as the armature reaches its end position, upon collision of the armature with the pole face of the capturing electromagnet an impact noise is generated which is not only transmitted as a sound wave to the environment but is also transmitted as a body vibration to the internal-combustion engine and, in case of vehicles, it is even transferred to the vehicle body.